A new asteroid (Echinodermata) faunule from the Early Cretaceous (Barremian) of Morocco

Abstract

An asteroid (Echinodermata) faunule of four taxa representing three surviving families and a probable fourth is described from the Barremian (Early Cretaceous) of Morocco, northwest Africa. The four together suggest limited morphologic evolution since the Cretaceous but biogeographic and depth patterns have changed. Marocaster coronatus n. gen. n. sp. (Valvatida, Goniasteridae) combines apparent derived features of the dorsal disk and superomarginal shape with more stemward expressions of the abactinal ossicles. Betelgeusia orientalis n. sp. is a fourth Mesozoic occurrence of the Radiasteridae (Paxillosida), the new species similar to earlier occurrences from the Middle Jurassic of India, the Early Cretaceous of Texas, and the Late Cretaceous of Europe. Reported modern occurrences of the family are few, widely scattered, and limited to deeper water; the extinct species together testify to a once-broader familial distribution. Dipsacaster africanus n. sp., a member of the Astropectinidae (Paxillosida), is remarkably similar to extant congeners. Dipsacaster today is widely distributed in the Pacific Ocean but occurrences in the Atlantic are few. Because of preservation, a single small specimen of the Zoroasteridae? (Forcipulatida) cannot be identified with certainty. Extant zoroasterids are deep-water in distribution, although shallow-water Eocene representatives are known.

Un astropectínido (Echinodermata, Asteroidea) cretácico temprano de Patagonia (Argentina): Una nueva especie y el registro más antiguo de la familia para el Hemisferio Sur.

“…Articulated remains are extremely rare, and are expected to usually happen in storm-generated beds or other kind of rapid deposition events (Hess, 1972;Goldring and Stephenson, 1972;Meyer, 1984Meyer, , 1988Jagt, 2000). For example, Blake and Reboul (2011) reported numerous specimens from Morocco at depths of 30 m or less, in a situation more similar to the case under study here, even though their material came from limestones rather than sandstones. Taking into account that seastars are a conservative group regarding general morphological features (Jagt, 2000), and particularly in the case of Tethyaster (according to Breton, 1996), and given that no significant change is observed in the genus since its first representatives known from the Jurassic (see below), Mesozoic Tethyaster specimens were most likely capable of self-burial as well.…”

“…Known Cretaceous records are mostly European, with other occurrences taking place in Canada, USA and northern Africa (e.g., Blake and Reboul, 2011;Blake and Sprinkle, 1996;Blake and Sturgeon, 1995;Breton, 1996;de Loriol, 1873;Hall and Moore, 1990;Hérenger, 1944;Hess, 1970;Hess and Blake, 1995;Jagt, 2000;Néraudeau and Breton, 1993;Neumann and Hess, 2001;Neumann and Jagt, 2011;Smith et al, 1988;Spencer and Wright, 1966;Villier, 2008;Villier et al, 2007;Vullo et al, 2003). Regarding Lower Cretaceous records, Villier et al (2007) have suggested that the sparseness of astropectinid occurrences could be more related to certain biases rather than being a reflection of low starfish diversity.…”

<p><strong>Comments on "The phylogeny of post-Palaeozoic Asteroidea </strong><strong>(Neoasteroidea, Echinodermata)" by A.S. Gale and perspectives </strong><strong>on the systematics of the Asteroidea</strong></p>

“…Many changes to the taxonomic assignments of Blake (1986), Blake and Reid (1998), Blake et al (2000), Blake and Hagdorn (2003), and Blake et al (2006) were proposed by Gale (2005Gale ( , 2011a. All suggestions are rejected here and in Blake & Reboul (2011). Interpretations of Gale (2011a) were not tested through inclusion of fossils in his phylogenetic analysis; perhaps such inclusion would have enabled a single integrated systematic section in his study, rather than division of an inferred single phylogenetic sequence into separate extant and fossil sections.…”

“…Benthogenia cribellosa is peculiar in a number of other aspects, perhaps most obvious, the comparatively extended arms, an oddity of uncertain significance found in other Phillippine asteroids (Fisher 1919). Gale (2011a: 57) proposed transfer of Betelgeusia Blake & Reid to the Astropectinidae; radiasterid affinities were reaffirmed in Blake & Reboul (2011).…”

Asteroids (Echinodermata) from the Barremian (Lower Cretaceous) of the Agadir Basin, west Morocco

“…Taxa recorded from these sites have been referred to the families Astropectinidae, Goniasteridae, and Radiasteridae. Blake and Reboul (2011) also noted a poorly preserved asteroid with affinities to the family Zoroasteridae, but the material did not provide sufficient features to enable a full description.…”